| Popis: |
The exact differential diagnosis of iron overload syndromes is mandatory as important therapeutic consequences may derive from a correct diagnosis, especially when hemochromatosis is present. To facilitate diagnostic and therapeutic decisions algorithms and probabilistic calculations based on different frequencies of clinical symptoms and typical laboratory findings of the diseases in question have been proposed. Overestimation and/or underestimation of clinical symptoms and/or laboratory findings in using such calculations, however, may lead to incorrect diagnosis and therapy as demonstrated in this case. We report on a 62-year-old patient with arthralgia, pathologic glucose metabolism, brown skin pigmentation and excessively elevated ferritin and transferrin saturation levels, which initially were interpreted as signs of the assumed underlying disease (hemo-chromatosis) based on a high initial suspicion level and further corroborated by Bayesian probability analysis yielding a probability 99.0 % for the presence of hemochromatosis. Because of this high probability and the patient's wish for treatment phlebotomy was started, but stopped after having obtained negative results of genetic testing and normal quantitative liver iron values. The diagnosis of hemochromatosis had to be revised and symptoms and laboratory findings of this patient were found to be compatible with chronic fatty liver and pathologically altered iron metabolism due to chronic alcohol intake which the patient has initially concealed. The joint pain was explained in terms of chronic degenerative bone destruction, the impaired glucose tolerance seen as the consequence of obesity and the skin pigmentation was ascribed to sun exposure due to the patient's outdoor activities as a hobby farmer not evaluated during initial presentation. The implications and importance of unbiased history taking, critical interpretation of clinical symptoms and laboratory findings in using probabilistic calculations and diagnostic decision analysis are emphasized and the different mechanisms of iron metabolism in hemochromatosis and hemosiderosis are discussed. |
